Pub Date : 2025-02-17DOI: 10.1016/j.optcom.2025.131628
Hailiang Zhang , Hui Dong , Dora Juan Juan Hu , Perry Ping Shum
We propose and experimentally demonstrate a method to measure the fibre loss profile using a standard intensity-based phase-sensitive optical time-domain reflectometer (Φ-OTDR) without any hardware modifications. While Φ-OTDR is widely used for distributed acoustic sensing (DAS) applications, fibre loss measurement typically requires a separate OTDR system. Our study shows that by averaging the raw Φ-OTDR traces over time, the coherent backscattered light transitions into an incoherent superposition, producing a trace similar to that of a traditional OTDR. This work incorporates expanded experimental investigation and simulation of temperature fluctuations on the phase and birefringence in the loss measurement by Φ-OTDR. Three groups of simulations were conducted for two types of temperature variations during the averaging period, including linear temperature change, and sinusoidal change. Simulation results show that the simulated temperature variation profiles have minimal impact on the long-term averaged outcomes. Experimental results for a 15 km fibre link with intentionally introduced loss events demonstrate that Φ-OTDR can effectively and accurately measure both fibre loss and event locations. The obtained measurements closely align with those recorded using a conventional OTDR system, confirming the reliability and precision of the proposed method. Notably, the system successfully detected an event with a minimal loss of about 0.13 dB. Additionally, the measurement differences of event losses and linear section attenuations were ≤0.1 dB and ≤0.02 dB/km, respectively. This technique offers a cost-effective solution for integrating OTDR functionality into existing Φ-OTDR systems.
{"title":"Optical fibre loss profile measurement by using intensity-based phase-sensitive OTDR","authors":"Hailiang Zhang , Hui Dong , Dora Juan Juan Hu , Perry Ping Shum","doi":"10.1016/j.optcom.2025.131628","DOIUrl":"10.1016/j.optcom.2025.131628","url":null,"abstract":"<div><div>We propose and experimentally demonstrate a method to measure the fibre loss profile using a standard intensity-based phase-sensitive optical time-domain reflectometer (Φ-OTDR) without any hardware modifications. While Φ-OTDR is widely used for distributed acoustic sensing (DAS) applications, fibre loss measurement typically requires a separate OTDR system. Our study shows that by averaging the raw Φ-OTDR traces over time, the coherent backscattered light transitions into an incoherent superposition, producing a trace similar to that of a traditional OTDR. This work incorporates expanded experimental investigation and simulation of temperature fluctuations on the phase and birefringence in the loss measurement by Φ-OTDR. Three groups of simulations were conducted for two types of temperature variations during the averaging period, including linear temperature change, and sinusoidal change. Simulation results show that the simulated temperature variation profiles have minimal impact on the long-term averaged outcomes. Experimental results for a 15 km fibre link with intentionally introduced loss events demonstrate that Φ-OTDR can effectively and accurately measure both fibre loss and event locations. The obtained measurements closely align with those recorded using a conventional OTDR system, confirming the reliability and precision of the proposed method. Notably, the system successfully detected an event with a minimal loss of about 0.13 dB. Additionally, the measurement differences of event losses and linear section attenuations were ≤0.1 dB and ≤0.02 dB/km, respectively. This technique offers a cost-effective solution for integrating OTDR functionality into existing Φ-OTDR systems.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"580 ","pages":"Article 131628"},"PeriodicalIF":2.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.optcom.2025.131630
Hongwei Zhao, Chao Chen, Jianhua Ji
In this paper, we novelly proposed a hybrid network solution of optical code division multiple access (OCDMA) and unmanned aerial vehicle (UAV) based free space optical (FSO) communication technologies, namely UAV-assisted FSO-OCDMA communication system, which can be used in secure communication scenarios such as military reconnaissance. This paper describes the architecture of the proposed UAV-assisted FSO-OCDMA communication network as well as the experimental scheme in detail. In this paper, we investigate the performance impact of different atmospheric turbulence intensities on the proposed system based on a 10 Gb/s FSO-OCDMA communication experiment platform. It is worth noting that this is the first time to experimentally study the security performance of OCDMA encoded FSO system considering UAV's vibration reception through a mechanical vibration platform. Furthermore, eye diagrams and average bit error rate (BER) metrics are used to represent the impact of atmospheric turbulence and vibration effects on system transmission performance in single-user and dual-user scenarios considering the presence of an eavesdropper. The experimental results show that the system can meet the reliability of communication in single-user and dual-user scenarios at a data rate of 10 Gb/s. When the transmission power is −8.5 dBm and the vibration amplitude is 0.20 mm under weak turbulence for a dual-user system, the BER of the legitimator and eavesdropper is 8.78 × 10−4 and 0.0276, respectively. The eavesdropper was unable to successfully recover the signal, indicating that the considered system can achieve security communication. Therefore, the UAV-assisted FSO-OCDMA system can be used as a communication service to provide flexible deployment, high rate, and high security.
{"title":"Experimental investigation of UAV-assisted FSO-CDMA system over turbulent channel with vibration effects","authors":"Hongwei Zhao, Chao Chen, Jianhua Ji","doi":"10.1016/j.optcom.2025.131630","DOIUrl":"10.1016/j.optcom.2025.131630","url":null,"abstract":"<div><div>In this paper, we novelly proposed a hybrid network solution of optical code division multiple access (OCDMA) and unmanned aerial vehicle (UAV) based free space optical (FSO) communication technologies, namely UAV-assisted FSO-OCDMA communication system, which can be used in secure communication scenarios such as military reconnaissance. This paper describes the architecture of the proposed UAV-assisted FSO-OCDMA communication network as well as the experimental scheme in detail. In this paper, we investigate the performance impact of different atmospheric turbulence intensities on the proposed system based on a 10 Gb/s FSO-OCDMA communication experiment platform. It is worth noting that this is the first time to experimentally study the security performance of OCDMA encoded FSO system considering UAV's vibration reception through a mechanical vibration platform. Furthermore, eye diagrams and average bit error rate (BER) metrics are used to represent the impact of atmospheric turbulence and vibration effects on system transmission performance in single-user and dual-user scenarios considering the presence of an eavesdropper. The experimental results show that the system can meet the reliability of communication in single-user and dual-user scenarios at a data rate of 10 Gb/s. When the transmission power is −8.5 dBm and the vibration amplitude is 0.20 mm under weak turbulence for a dual-user system, the BER of the legitimator and eavesdropper is 8.78 × 10<sup>−4</sup> and 0.0276, respectively. The eavesdropper was unable to successfully recover the signal, indicating that the considered system can achieve security communication. Therefore, the UAV-assisted FSO-OCDMA system can be used as a communication service to provide flexible deployment, high rate, and high security.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"581 ","pages":"Article 131630"},"PeriodicalIF":2.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-15DOI: 10.1016/j.optcom.2025.131624
Yu Pan , Jin Wen , Ying Zhang , Shuangchao Qu , Chenglong Wang , Lan Yin , Chengju Ma , Wei Fan , Yuening Jiang , Hongsen Zhao , Dingkang Zhang
Compared with the traditional forward design method, the inverse design method has become a hot research topic because of its high degree of freedom and flexibility within the field of silicon-based photonic devices. In this work, we propose ultra-compact and ultra-wide bandwidth polarization beam splitter (PBS) by inverse design method on a standard silicon-on-isolator platform. The structure of the PBS consists of a hybrid plasmonic waveguide coupled to a subwavelength grating waveguide in an asymmetric directional coupler. The unique polarization diversity of the hybrid plasmonic waveguide enables TE and TM polarizations to be transmitted in two different layers, which is expected to break through the size limitation of photonic devices. The introduction of subwavelength grating effectively reduces the beat length of TE polarization and significantly broadens the working bandwidth of PBS. In order to optimize the parameters, the particle swarm optimization algorithm is employed, with the aim of searching to obtain a set of optimized parameters that satisfy both the TE polarization phase matching and the TM polarization phase mismatch. The numerical results demonstrate that the coupling length of the PBS is only 2.36 μm, and both the bandwidths for the TE and TM polarizations exceed 123 nm, which effectively covers the entire C-band. At the wavelength of 1550 nm, the extinction ratio for TE (TM) is 12.96 dB (20.13 dB) and the insertion loss is only 0.23 dB (1.12 dB). The fabrication tolerance of the PBS is also analyzed, and the results show that the device exhibits good tolerance to fabrication errors. The PBS obtained by inverse design has the characteristics of large bandwidth and small size, which is conducive to the development of photonic devices in the direction of integration.
{"title":"Ultra-compact asymmetric polarization beam splitter based on hybrid plasmonic waveguide and subwavelength grating utilizing particle swarm optimization algorithm","authors":"Yu Pan , Jin Wen , Ying Zhang , Shuangchao Qu , Chenglong Wang , Lan Yin , Chengju Ma , Wei Fan , Yuening Jiang , Hongsen Zhao , Dingkang Zhang","doi":"10.1016/j.optcom.2025.131624","DOIUrl":"10.1016/j.optcom.2025.131624","url":null,"abstract":"<div><div>Compared with the traditional forward design method, the inverse design method has become a hot research topic because of its high degree of freedom and flexibility within the field of silicon-based photonic devices. In this work, we propose ultra-compact and ultra-wide bandwidth polarization beam splitter (PBS) by inverse design method on a standard silicon-on-isolator platform. The structure of the PBS consists of a hybrid plasmonic waveguide coupled to a subwavelength grating waveguide in an asymmetric directional coupler. The unique polarization diversity of the hybrid plasmonic waveguide enables TE and TM polarizations to be transmitted in two different layers, which is expected to break through the size limitation of photonic devices. The introduction of subwavelength grating effectively reduces the beat length of TE polarization and significantly broadens the working bandwidth of PBS. In order to optimize the parameters, the particle swarm optimization algorithm is employed, with the aim of searching to obtain a set of optimized parameters that satisfy both the TE polarization phase matching and the TM polarization phase mismatch. The numerical results demonstrate that the coupling length of the PBS is only 2.36 μm, and both the bandwidths for the TE and TM polarizations exceed 123 nm, which effectively covers the entire C-band. At the wavelength of 1550 nm, the extinction ratio for TE (TM) is 12.96 dB (20.13 dB) and the insertion loss is only 0.23 dB (1.12 dB). The fabrication tolerance of the PBS is also analyzed, and the results show that the device exhibits good tolerance to fabrication errors. The PBS obtained by inverse design has the characteristics of large bandwidth and small size, which is conducive to the development of photonic devices in the direction of integration.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"582 ","pages":"Article 131624"},"PeriodicalIF":2.2,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-15DOI: 10.1016/j.optcom.2025.131601
Vladimir I. Kruglov , Houria Triki
We demonstrate the possibility of stopping the soliton pulses in optical waveguide with varying and constant parameters exhibiting a Kerr nonlinear response. By using the similarity transformation, we have found the constraint condition for varying waveguide parameters and derive the exact analytical solutions for self-similar bright, kink, dark and rectangular solitary and periodic waves for nonlinear Schrödinger equation with variable coefficients. All these generalized wave solutions depend on five arbitrary parameters and two free integration constants. It is found that the velocity of solitons is related to a free parameter , which play an important role in the dynamic behavior of soliton’s evolution. The precise expression of soliton’s velocity shows that the solitons can be nearly stopped for appropriate values of free parameter . The possibility for stopping of soliton pulses can also be realized when all parameters of nonlinear Schrödinger equation are constant. The numerical simulations show that the stopping behavior of solitons and rectangular solitary waves can be achieved for appropriate values of free parameters characterizing these wave solutions. The results also demonstrate that the stopping motion of solitons can be completely attained by use of an optical fiber whose first- and second-order dispersions decrease exponentially along its length if considering large distance and suitable values of free parameter .
{"title":"Stopping of generalized solitary and periodic waves in optical waveguide with varying and constant parameters","authors":"Vladimir I. Kruglov , Houria Triki","doi":"10.1016/j.optcom.2025.131601","DOIUrl":"10.1016/j.optcom.2025.131601","url":null,"abstract":"<div><div>We demonstrate the possibility of stopping the soliton pulses in optical waveguide with varying and constant parameters exhibiting a Kerr nonlinear response. By using the similarity transformation, we have found the constraint condition for varying waveguide parameters and derive the exact analytical solutions for self-similar bright, kink, dark and rectangular solitary and periodic waves for nonlinear Schrödinger equation with variable coefficients. All these generalized wave solutions depend on five arbitrary parameters and two free integration constants. It is found that the velocity of solitons is related to a free parameter <span><math><mi>q</mi></math></span>, which play an important role in the dynamic behavior of soliton’s evolution. The precise expression of soliton’s velocity shows that the solitons can be nearly stopped for appropriate values of free parameter <span><math><mi>q</mi></math></span>. The possibility for stopping of soliton pulses can also be realized when all parameters of nonlinear Schrödinger equation are constant. The numerical simulations show that the stopping behavior of solitons and rectangular solitary waves can be achieved for appropriate values of free parameters characterizing these wave solutions. The results also demonstrate that the stopping motion of solitons can be completely attained by use of an optical fiber whose first- and second-order dispersions decrease exponentially along its length if considering large distance and suitable values of free parameter <span><math><mi>q</mi></math></span>.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"580 ","pages":"Article 131601"},"PeriodicalIF":2.2,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-15DOI: 10.1016/j.optcom.2025.131623
Chen Mo , Xiaoli Liu , Zewei Cai , Jiangtao Xi , Yanguang Yu , Jun Tong
Light field imaging is applied in fields like virtual reality, 3D reconstruction and medical imaging by capturing spatial and angular information of light to enable more immersive and flexible visual experiences. However, light-field imaging systems often face challenges such as high complexity and limited resolution. In recent years, lensless imaging systems have garnered significant attention for their potential to overcome the limitations of traditional lens-based architectures. Despite their advantages, lensless light-field imaging suffers from notable errors in light-field reconstruction. This paper presents an enhanced Point Spread Function (PSF) segmentation method for lensless light-field imaging, designed to improve the quality of light-field reconstruction. The proposed approach initially divides the PSF into pairs of complementary sub-aperture PSFs, with one PSF targeting the desired sub-aperture area and the other serving as an auxiliary for reconstruction. This allows for the separate reconstruction of sub-aperture images for each area. To assess the light-field reconstruction performance, the imaging quality and angular consistency of various PSF segmentation methods are compared using digital refocusing, epipolar plane images (EPI), depth maps, peak signal-to-noise ratio (PSNR), and structural similarity index (SSIM). Furthermore, the effectiveness of the proposed methodology is validated through experimental results and theoretical analysis. It is demonstrated that lensless light-field imaging using complementary segmentation of the PSF achieves high-quality light-field reconstruction.
{"title":"Lensless light-field imaging through complementary segmentation of PSF","authors":"Chen Mo , Xiaoli Liu , Zewei Cai , Jiangtao Xi , Yanguang Yu , Jun Tong","doi":"10.1016/j.optcom.2025.131623","DOIUrl":"10.1016/j.optcom.2025.131623","url":null,"abstract":"<div><div>Light field imaging is applied in fields like virtual reality, 3D reconstruction and medical imaging by capturing spatial and angular information of light to enable more immersive and flexible visual experiences. However, light-field imaging systems often face challenges such as high complexity and limited resolution. In recent years, lensless imaging systems have garnered significant attention for their potential to overcome the limitations of traditional lens-based architectures. Despite their advantages, lensless light-field imaging suffers from notable errors in light-field reconstruction. This paper presents an enhanced Point Spread Function (PSF) segmentation method for lensless light-field imaging, designed to improve the quality of light-field reconstruction. The proposed approach initially divides the PSF into pairs of complementary sub-aperture PSFs, with one PSF targeting the desired sub-aperture area and the other serving as an auxiliary for reconstruction. This allows for the separate reconstruction of sub-aperture images for each area. To assess the light-field reconstruction performance, the imaging quality and angular consistency of various PSF segmentation methods are compared using digital refocusing, epipolar plane images (EPI), depth maps, peak signal-to-noise ratio (PSNR), and structural similarity index (SSIM). Furthermore, the effectiveness of the proposed methodology is validated through experimental results and theoretical analysis. It is demonstrated that lensless light-field imaging using complementary segmentation of the PSF achieves high-quality light-field reconstruction.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"580 ","pages":"Article 131623"},"PeriodicalIF":2.2,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-15DOI: 10.1016/j.optcom.2025.131625
Laxminarayan, Praveen Kumar
Composite vortex (CoV) beams are the structured beams represented through the superposition of multiple Laguerre-Gaussian modes. Composite vortices have recently gained importance owing to their unique properties originating from the multiple-phase singularities, and therefore, techniques for their generation and characterization play a vital role. The present study reports a method for identifying the topological charges of singular points embedded in CoV beams using self-referenced interferometry under the effect of atmospheric turbulence. The beam carrying composite vortices interferes with its own conjugate copy, resulting in a well-defined interference pattern, which, on analysis, reveals the sign and magnitude of topological charge. Simulation and experimental results have been presented that verify the effectiveness of the proposed technique. The results show that the proposed method can effectively identify the multiple-phase singularities through interferometry without the use of any additional reference beam.
{"title":"Charge identification of composite vortex beams through self-referenced interferometry","authors":"Laxminarayan, Praveen Kumar","doi":"10.1016/j.optcom.2025.131625","DOIUrl":"10.1016/j.optcom.2025.131625","url":null,"abstract":"<div><div>Composite vortex (CoV) beams are the structured beams represented through the superposition of multiple Laguerre-Gaussian modes. Composite vortices have recently gained importance owing to their unique properties originating from the multiple-phase singularities, and therefore, techniques for their generation and characterization play a vital role. The present study reports a method for identifying the topological charges of singular points embedded in CoV beams using self-referenced interferometry under the effect of atmospheric turbulence. The beam carrying composite vortices interferes with its own conjugate copy, resulting in a well-defined interference pattern, which, on analysis, reveals the sign and magnitude of topological charge. Simulation and experimental results have been presented that verify the effectiveness of the proposed technique. The results show that the proposed method can effectively identify the multiple-phase singularities through interferometry without the use of any additional reference beam.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"581 ","pages":"Article 131625"},"PeriodicalIF":2.2,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Narrow linewidth quantum dot (QD) lasers are in demand for practical applications that require a high degree of temporal coherence. Toward achieving narrow linewidth laser, this work numerically investigates the impact of external optical feedback on the frequency noise (FN) and the intrinsic spectral linewidth characteristics of QD lasers epitaxially grown on silicon (Si) substrate. Modified Lang-Kobayashi rate equations have been used to calculate the effect of feedback ratio, the feedback phase, and the non-radiative recombination lifetime in both short- and long-cavity regimes. We found that although in the short-cavity regime, the spectral linewidth can be either narrowed or broadened depending on the feedback phase. However, in the long-cavity regime, effective linewidth reduction is available for sufficiently high feedback ratios (leading to C > 1) for any feedback phase. The linewidth is reduced from 630 kHz in the free-running case to around 8 kHz, when the feedback ratio is increased from zero to −10 dB, this is equal to a reduction of 19 dB in the linewidth. These findings provide a simple and cost-effective way for producing narrow linewidth Si-based QD lasers appropriate for advancing coherent optical technology on silicon.
{"title":"Narrowing of spectral linewidth in epitaxial quantum dot lasers on silicon: Comparison of short- and long-cavity feedback conditions","authors":"Zahra Ebrahimzadeh, Hamid Nadgaran, Mahmood Hosseini Farzad","doi":"10.1016/j.optcom.2025.131626","DOIUrl":"10.1016/j.optcom.2025.131626","url":null,"abstract":"<div><div>Narrow linewidth quantum dot (QD) lasers are in demand for practical applications that require a high degree of temporal coherence. Toward achieving narrow linewidth laser, this work numerically investigates the impact of external optical feedback on the frequency noise (FN) and the intrinsic spectral linewidth characteristics of QD lasers epitaxially grown on silicon (Si) substrate. Modified Lang-Kobayashi rate equations have been used to calculate the effect of feedback ratio, the feedback phase, and the non-radiative recombination lifetime in both short- and long-cavity regimes. We found that although in the short-cavity regime, the spectral linewidth can be either narrowed or broadened depending on the feedback phase. However, in the long-cavity regime, effective linewidth reduction is available for sufficiently high feedback ratios (leading to C > 1) for any feedback phase. The linewidth is reduced from 630 kHz in the free-running case to around 8 kHz, when the feedback ratio is increased from zero to −10 dB, this is equal to a reduction of 19 dB in the linewidth. These findings provide a simple and cost-effective way for producing narrow linewidth Si-based QD lasers appropriate for advancing coherent optical technology on silicon.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"582 ","pages":"Article 131626"},"PeriodicalIF":2.2,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143477990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-14DOI: 10.1016/j.optcom.2025.131618
Arya Gopinath, Jeena Rose Jose, Sincy Anna Oommen, Cyriac Joseph, P.R. Biju
The structural and photoluminescence studies of a series of Sr2Ca(1-x)TeO6:xEu3+ phosphors synthesized through solid state reaction method were investigated in this work. The phosphor exhibits needle like morphology which is advantageous for its use in photovoltaic cells and lighting applications. On exciting Sr2CaTeO6:Eu3+ phosphors with blue light (λ = 464 nm), the phosphors exhibit bright red emission at 615 nm, which corresponds to the transition of Eu3+ in Sr2CaTeO6 host, originating from 5D0→7F2 electric dipole transition. The optimum concentration of Eu3+ in this host is found to be 4 mol% and the concentration quenching phenomenon is attributed due to dipole-dipole interaction of neighbouring Eu3+ ions. The calculated CIE coordinates of the prepared phosphors are similar to the NTSC red phosphor and commercial red phosphors. These results suggests that the Sr2CaTeO6:Eu3+ phosphors are potential candidate to incorporate in WLEDs as an excellent red emitting phosphor.
{"title":"Luminescence studies of needle like structured Sr2Ca(1-x)TeO6:xEu3+ phosphors for solid state lighting applications","authors":"Arya Gopinath, Jeena Rose Jose, Sincy Anna Oommen, Cyriac Joseph, P.R. Biju","doi":"10.1016/j.optcom.2025.131618","DOIUrl":"10.1016/j.optcom.2025.131618","url":null,"abstract":"<div><div>The structural and photoluminescence studies of a series of Sr<sub>2</sub>Ca<sub>(1-x)</sub>TeO<sub>6</sub>:xEu<sup>3+</sup> phosphors synthesized through solid state reaction method were investigated in this work. The phosphor exhibits needle like morphology which is advantageous for its use in photovoltaic cells and lighting applications. On exciting Sr<sub>2</sub>CaTeO<sub>6</sub>:Eu<sup>3+</sup> phosphors with blue light (λ = 464 nm), the phosphors exhibit bright red emission at 615 nm, which corresponds to the transition of Eu<sup>3+</sup> in Sr<sub>2</sub>CaTeO<sub>6</sub> host, originating from <sup>5</sup>D<sub>0</sub>→<sup>7</sup>F<sub>2</sub> electric dipole transition. The optimum concentration of Eu<sup>3+</sup> in this host is found to be 4 mol% and the concentration quenching phenomenon is attributed due to dipole-dipole interaction of neighbouring Eu<sup>3+</sup> ions. The calculated CIE coordinates of the prepared phosphors are similar to the NTSC red phosphor and commercial red phosphors. These results suggests that the Sr<sub>2</sub>CaTeO<sub>6</sub>:Eu<sup>3+</sup> phosphors are potential candidate to incorporate in WLEDs as an excellent red emitting phosphor.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"580 ","pages":"Article 131618"},"PeriodicalIF":2.2,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, propagation characteristics of auto-focusing Bessel Gaussian beam (ABGB) and auto-focusing Bessel Gaussian vortex beam (ABGVB) with double foci in the chiral medium are studied for the first time. Effects of beam parameters, such as the beam waist width, the initial beam focal length, the topological charge of optical vortex, and the chiral medium parameter on the auto-focusing behavior of ABGB and ABGVB are investigated. The results indicate that by adjusting the beam waist width of ABGB could manipulate the focal length depth and the auto-focusing ability of left-circularly polarized (LCP) and right-circularly polarized (RCP) components in the chiral media. The focal lengths, the focal length depths, and the auto-focusing abilities of LCP and RCP components can be controlled by the initial beam focal length of ABGB. The focal length and the focal length depth of RCP can be modulated by the chiral medium parameter effectively. Optical vortex results in a dark hollow channel in the optical field of ABGVB propagating in the chiral media, and the topological charge determines the width of dark hollow. The optical vortex and the beam waist width do not affect the focal length of LCP and RCP, while the initial beam focal length of ABGVB and the chiral medium parameter could be adopted to manipulate the focal lengths of ABGVB, especially the manipulation of RCP focal length.
{"title":"Propagation dynamics of auto-focusing Bessel Gaussian beam in a chiral medium","authors":"Zihan Zhao, Zhiwei Mi, Ruojun Wei, Liping Zhang, Benyi Wang, Zhongsheng Man, Xiaolu Ge","doi":"10.1016/j.optcom.2025.131617","DOIUrl":"10.1016/j.optcom.2025.131617","url":null,"abstract":"<div><div>In this paper, propagation characteristics of auto-focusing Bessel Gaussian beam (ABGB) and auto-focusing Bessel Gaussian vortex beam (ABGVB) with double foci in the chiral medium are studied for the first time. Effects of beam parameters, such as the beam waist width, the initial beam focal length, the topological charge of optical vortex, and the chiral medium parameter on the auto-focusing behavior of ABGB and ABGVB are investigated. The results indicate that by adjusting the beam waist width of ABGB could manipulate the focal length depth and the auto-focusing ability of left-circularly polarized (LCP) and right-circularly polarized (RCP) components in the chiral media. The focal lengths, the focal length depths, and the auto-focusing abilities of LCP and RCP components can be controlled by the initial beam focal length of ABGB. The focal length and the focal length depth of RCP can be modulated by the chiral medium parameter effectively. Optical vortex results in a dark hollow channel in the optical field of ABGVB propagating in the chiral media, and the topological charge determines the width of dark hollow. The optical vortex and the beam waist width do not affect the focal length of LCP and RCP, while the initial beam focal length of ABGVB and the chiral medium parameter could be adopted to manipulate the focal lengths of ABGVB, especially the manipulation of RCP focal length.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"580 ","pages":"Article 131617"},"PeriodicalIF":2.2,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-14DOI: 10.1016/j.optcom.2025.131621
Xiaohui Wang , Jiawei Rui , Liang Xu , Hui Zhang , Xinchen Ji , Shuai Mao , Zhiang Gao , Chenglong Jiang , Dongdong Deng , Yang Wang , Yingxiong Song , Fufei Pang , Liyun Zhuang
In order to enhance channel capacity (CC) and propagation distance, a new radio (NR) in sub-THz band (STB) is employed and propagated over an orbital angular momentum (OAM) fiber for delivering user data by OAM-based space-division multiplexing (SDM). For propagating the STB wave, A weakly-coupled optical fiber (WCOF) with four layers is designed and manufactured in our Lab for propagation OAM beams, where 6 OAM groups (OAMGs) can be supported with a larger difference of effective refraction index among different OAMGs. A propagation loss of less than 3.2 dBm/km for 6 OAMGs at 1550 nm is achieved in the proposed WOCF. A probative platform is also built for denoting the feasibility of the proposed scheme. Besides OAMG 0 without OAM, the OAM mode with an integral topological charge (TC) of −1/-2/-3/-4/-5 is utilized as the representative of OAMG 1/2/3/4/5 in the experiments, respectively. The captured intensities and interference patterns depict that the propagated five OAM beams can be successfully detected at receiving side, which shows that the proposed method is feasible. Bit error rates (BERs) and constellation plots (CPs) are also adopted for analyzing the performances of the proposed concept, respectively. When the SDM is employed or not, the measured BERs for five OAM channels with TC = −1, −2, −3, −4 and −5 degrade by 0.61/2.8, 0.83/3.21, 1.27/3.64, 1.63/4.05 and 1.98/4.39 dB compared with “BTB”, respectively, where a less than 2/5 dB degradation without/with SDM can be achieved. A less than 3 dB degradation for five OAM modes between “W/O SDM” and “W/SDM” can be observed, which can be contributed to the crosstalk induced by SDM. In addition, the measured CPs of 16-quadrature amplitude modulation (QAM) in five OAM channels are consistent with the measured BER distributions at an optical signal to noise ratio of 15.2 dB. Moreover, the influences of data speed and fiber length on the BER distributions are also explored, where the BER of the monitored channel of TC = −5 decreases as the data speed or fiber length increases. Compared to the data rate, the fiber length is more sensitive to fiber length. Although, the propagation loss can be degraded by reducing contrast of refraction index against the cladding (CRIC) between core layer and cladding for achieving a long-haul propagation, the number of OAM modes is also decreased. Consequently, the propagation distance and the supported number of OAM modes should be overall considered for balance in practical applications.
{"title":"Delivering 5G NR data by multiplexing OAM modes over an OAM fiber","authors":"Xiaohui Wang , Jiawei Rui , Liang Xu , Hui Zhang , Xinchen Ji , Shuai Mao , Zhiang Gao , Chenglong Jiang , Dongdong Deng , Yang Wang , Yingxiong Song , Fufei Pang , Liyun Zhuang","doi":"10.1016/j.optcom.2025.131621","DOIUrl":"10.1016/j.optcom.2025.131621","url":null,"abstract":"<div><div>In order to enhance channel capacity (CC) and propagation distance, a new radio (NR) in sub-THz band (STB) is employed and propagated over an orbital angular momentum (OAM) fiber for delivering user data by OAM-based space-division multiplexing (SDM). For propagating the STB wave, A weakly-coupled optical fiber (WCOF) with four layers is designed and manufactured in our Lab for propagation OAM beams, where 6 OAM groups (OAMGs) can be supported with a larger difference of effective refraction index among different OAMGs. A propagation loss of less than 3.2 dBm/km for 6 OAMGs at 1550 nm is achieved in the proposed WOCF. A probative platform is also built for denoting the feasibility of the proposed scheme. Besides OAMG 0 without OAM, the OAM mode with an integral topological charge (TC) of −1/-2/-3/-4/-5 is utilized as the representative of OAMG 1/2/3/4/5 in the experiments, respectively. The captured intensities and interference patterns depict that the propagated five OAM beams can be successfully detected at receiving side, which shows that the proposed method is feasible. Bit error rates (BERs) and constellation plots (CPs) are also adopted for analyzing the performances of the proposed concept, respectively. When the SDM is employed or not, the measured BERs for five OAM channels with TC = −1, −2, −3, −4 and −5 degrade by 0.61/2.8, 0.83/3.21, 1.27/3.64, 1.63/4.05 and 1.98/4.39 dB compared with “BTB”, respectively, where a less than 2/5 dB degradation without/with SDM can be achieved. A less than 3 dB degradation for five OAM modes between “W/O SDM” and “W/SDM” can be observed, which can be contributed to the crosstalk induced by SDM. In addition, the measured CPs of 16-quadrature amplitude modulation (QAM) in five OAM channels are consistent with the measured BER distributions at an optical signal to noise ratio of 15.2 dB. Moreover, the influences of data speed and fiber length on the BER distributions are also explored, where the BER of the monitored channel of TC = −5 decreases as the data speed or fiber length increases. Compared to the data rate, the fiber length is more sensitive to fiber length. Although, the propagation loss can be degraded by reducing contrast of refraction index against the cladding (CRIC) between core layer and cladding for achieving a long-haul propagation, the number of OAM modes is also decreased. Consequently, the propagation distance and the supported number of OAM modes should be overall considered for balance in practical applications.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"580 ","pages":"Article 131621"},"PeriodicalIF":2.2,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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